Air-cooled fuel cell system

Abstract

To provide a fuel cell system that can prevent deterioration of a fuel cell.SOLUTION: A fuel cell system comprises a fuel cell, a hydrogen system, a reaction air system, and a cooling air system. The fuel cell has a reaction air channel and a cooling air channel having independent channel structures of reaction air and cooling air. The reaction air system has an inlet-side sealing valve at an inlet of the reaction air of the fuel cell, and an outlet-side sealing valve at an outlet of the reaction air of the fuel cell. During stop of the fuel cell system, the system stops supply of the reaction air to the fuel cell while continuing supply of hydrogen to the fuel cell and supply of the cooling air to the fuel cell, and closes the inlet-side sealing valve and the outlet-side sealing valve to seal a cathode of the fuel cell, and subsequently, stops supply of the hydrogen to the fuel cell while intermittently or successively continuing supply of the cooling air to the fuel cell.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present disclosure relates to air-cooled fuel cell systems. [Background technology]

[0002] Various technologies have been proposed regarding fuel cells (FCs), such as those disclosed in Patent Documents 1-6. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-216783 A [Patent Document 2] JP 2012-505496 A [Patent Document 3] JP 2007-115533 A [Patent Document 4] Japanese Patent Publication No. H06-022155 [Patent Document 5] JP 2022-185251 A [Patent Document 6] JP 2022-185247 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the case of an open-type air-cooled fuel cell, if the air supply is stopped during system shutdown, the cathode is exposed to air, causing an abnormal potential to develop in the fuel cell, leading to deterioration of the fuel cell.

[0005] The present disclosure has been made in consideration of the above-mentioned circumstances, and has as its main object to provide an air-cooled fuel cell system that can suppress deterioration of the fuel cell. [Means for solving the problem]

[0006] In a first embodiment of the present disclosure, there is provided an air-cooled fuel cell system, the fuel cell system includes a fuel cell, a hydrogen system that supplies hydrogen to the fuel cell, a reaction air system that supplies reaction air to the fuel cell, and a cooling air system that supplies cooling air to the fuel cell; the fuel cell has a reaction air flow path and a cooling air flow path having an independent flow path structure for the reaction air and the cooling air, the reaction air system has an inlet-side sealing valve at an inlet of the reaction air of the fuel cell, and an outlet-side sealing valve at an outlet of the reaction air of the fuel cell, The fuel cell system is characterized in that, when the system is shut down, the supply of reaction air to the fuel cell is stopped while continuing the supply of hydrogen to the fuel cell and the supply of cooling air to the fuel cell, and the inlet side sealing valve and the outlet side sealing valve are closed to seal the cathode of the fuel cell, and then the supply of hydrogen to the fuel cell is stopped while continuing the supply of cooling air to the fuel cell intermittently or continuously.

[0007] In the second embodiment of the present disclosure, in the first embodiment, the reaction air system has a reaction air blowing means, The cooling air system includes a cooling air blowing means, A hydrogen discharge passage of the hydrogen system may merge with a cooling air discharge passage of the cooling air system.

[0008] In a third embodiment of the present disclosure, the fuel cell system in the first embodiment further comprises an electrical system, The fuel cell system may connect the fuel cell to a power line of the electrical system when the system is shut down.

[0009] In a fourth embodiment of the present disclosure, in the first embodiment, the hydrogen system may have a hydrogen pump. Effect of the Invention

[0010] The fuel cell system of the present disclosure can suppress deterioration of the fuel cell. [Brief description of the drawings]

[0011] [Figure 1] 1 is an exploded perspective view showing an example of a single cell of a fuel cell provided in a fuel cell system according to the present disclosure; [Diagram 2] 1 is a schematic perspective view showing an example of a fuel cell stack provided in a fuel cell system according to the present disclosure. [Diagram 3] 1 is a system configuration diagram showing an example of a fuel cell system according to the present disclosure. [Figure 4] 2 is a circuit diagram showing an example of an electrical system provided in the fuel cell system of the present disclosure. FIG. [Diagram 5] 4 is a flowchart showing an example of control of the fuel cell system of the present disclosure. [Figure 6] 6 is a flowchart showing another example of the control of the fuel cell system according to the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, embodiments of the present disclosure will be described. Note that matters other than those specifically mentioned in this specification and necessary for implementing the present disclosure (for example, the general configuration and manufacturing process of a fuel cell system that does not characterize the present disclosure) can be understood as design matters of a person skilled in the art based on the prior art in the field. The present disclosure can be implemented based on the contents disclosed in this specification and the technical common sense in the field. Furthermore, the dimensional relationships (length, width, thickness, etc.) in the drawings do not reflect the actual dimensional relationships. In the present disclosure, the gas supplied to the anode of the fuel cell is a fuel gas (anode gas), and the gas supplied to the cathode of the fuel cell is an oxidant gas (cathode gas). The fuel gas is a gas that mainly contains hydrogen and may be hydrogen. The oxidant gas is a gas that contains oxygen and may be oxygen, air, etc. In the present disclosure, air as the oxidant gas is referred to as reaction air, and air as the cooling gas is referred to as cooling air.

[0013] The present disclosure provides an air-cooled fuel cell system, comprising: the fuel cell system includes a fuel cell, a hydrogen system that supplies hydrogen to the fuel cell, a reaction air system that supplies reaction air to the fuel cell, and a cooling air system that supplies cooling air to the fuel cell; the fuel cell has a reaction air flow path and a cooling air flow path having an independent flow path structure for the reaction air and the cooling air, the reaction air system has an inlet-side sealing valve at an inlet of the reaction air of the fuel cell, and an outlet-side sealing valve at an outlet of the reaction air of the fuel cell, The fuel cell system is characterized in that, when the system is shut down, the supply of reaction air to the fuel cell is stopped while continuing the supply of hydrogen to the fuel cell and the supply of cooling air to the fuel cell, and the inlet side sealing valve and the outlet side sealing valve are closed to seal the cathode of the fuel cell, and then the supply of hydrogen to the fuel cell is stopped while continuing the supply of cooling air to the fuel cell intermittently or continuously.

[0014] If air gets partially mixed into the anode due to cross leakage or other reasons while the fuel cell system is stopped, the catalyst layer is partially exposed to a high potential within the cell surface of the fuel cell, causing the catalyst layer to deteriorate. To prevent this situation, known as abnormal potential, it is necessary to consume oxygen in the cathode to keep the cell voltage sufficiently low during the shutdown process of the fuel cell system. In an air-cooled fuel cell, the volume of the fluid used for cooling is larger than in a water-cooled fuel cell, and the flow path structure for passing the fluid is also larger. For example, to cool 4kW, the amount of cooling water required is about 5L / min, whereas more than 10,000L / min of air is required. As the fuel cell continues to operate to generate electricity, the catalytic activity decreases due to the accumulation of oxides on the catalyst surface of the cathode, and the power generation efficiency decreases. In a typical open-type air-cooled fuel cell, the opening of the air system is large, making it difficult to seal the cathode when the fuel cell stops generating electricity. After power generation is stopped, air flows into the cathode, and oxygen also cross-leaks through the electrolyte membrane and enters the anode. This condition causes an abnormal potential in the fuel cell, and deterioration of the catalyst layer cannot be avoided. The main reason why the lifespan of a typical open-type air-cooled fuel cell is short, less than 1000 hours, is the occurrence of abnormal potential. Even if the cathode is sealed, the spatial volume is large, and it takes time to sufficiently reduce the oxygen in the cathode space, and if oxygen remains, the fuel cell will have an abnormal potential while the system is stopped. When air is put into the cathode and hydrogen into the anode without current flow, the potential of the fuel cell becomes high (about 0.95 to 1.05 V). In this state, the fuel cell begins to deteriorate, albeit slowly. In addition, an oxide film forms on the Pt catalyst, causing a decrease in the performance of the catalyst. To avoid this, the potential of the fuel cell may be kept constant at 0.85 V or less.

[0015] This disclosure relates to improving the performance of air-cooled fuel cells, and proposes a configuration and method for smoothly shutting down the system while preventing the occurrence of abnormal potential and deterioration of the fuel cell. A fuel cell having a flow path structure in which reaction air and cooling air are independent is shut down in a predetermined procedure. When the system is shut down, the supply of reaction air is stopped, the cathode is isolated from the outside of the fuel cell system, and the reaction air is consumed before shutting down, so deterioration of the fuel cell can be suppressed. Hydrogen discharged during the shutdown process can be diluted with cooling air.

[0016] The fuel cell system includes a fuel cell that generates electricity by reacting hydrogen with air, a hydrogen system that supplies the hydrogen needed to generate electricity to the fuel cell, a reaction air system that supplies reaction air to the fuel cell, and a cooling air system that supplies cooling air to the fuel cell to cool the heat generated by power generation.

[0017] The fuel cell may have only one unit cell (cell) of the fuel cell, or may be a fuel cell stack (stack) which is a laminate of a plurality of cells. In this disclosure, both cells and fuel cell stacks may be referred to as fuel cells. The number of cells stacked in the fuel cell stack is not particularly limited, and may be, for example, from 2 to several hundred. The fuel cell stack may have wavy cooling fins on each cell to provide cooling air flow paths. The fuel cell stack may have current collector plates, pressure plates, etc. at the ends in the stacking direction.

[0018] A fuel cell has a reactant air flow path (oxidant gas flow path) and a cooling air flow path (cooling gas flow path) with independent flow path structures for the reactant air and the cooling air, and may further have a hydrogen gas flow path (fuel gas flow path). A flow path structure in which the reaction air and the cooling air are separate means that there is no sharing of air between the flow paths from the supply of air to the fuel cell to the exhaust of air from the fuel cell. Note that the flow path for exhausting the air exhausted from the fuel cell to the outside of the fuel cell system may or may not be separate.

[0019] The cell may have a flow path structure for passing the reaction air and the cooling air such that the flow of the cooling air and the flow of the reaction air cross each other in a plan view. The flow of the cooling air and the flow of the reaction air may cross each other or be perpendicular to each other. The cell may have a power generation portion. The power generating section may have a rectangular shape in a plan view. The power generating section may be a membrane electrode assembly (MEA) including an electrolyte membrane and two electrodes. The electrolyte membrane may be a solid polymer electrolyte membrane. Examples of the solid polymer electrolyte membrane include a fluorine-based electrolyte membrane such as a thin film of perfluorosulfonic acid containing water, and a hydrocarbon-based electrolyte membrane. The electrolyte membrane may be, for example, a Nafion membrane (manufactured by DuPont). The two electrodes are the anode (fuel electrode or hydrogen electrode) and the cathode (oxygen electrode or air electrode). The electrodes include a catalyst layer and may include a gas diffusion layer as necessary, and the power generating portion may be a membrane electrode gas diffusion layer assembly (MEGA). The catalyst layer includes a catalyst, and the catalyst may include a catalytic metal that promotes an electrochemical reaction, an electrolyte having proton conductivity, and a carrier having electron conductivity. Examples of the catalytic metal that can be used include platinum (Pt) and alloys of Pt with other metals (e.g., Pt alloys mixed with cobalt and nickel, etc.) The catalytic metal used as the cathode catalyst and the catalytic metal used as the anode catalyst may be the same or different. The electrolyte may be a fluorine-based resin, etc. As the fluorine-based resin, for example, a Nafion solution, etc. may be used. The catalytic metal is supported on a carrier, and in each catalyst layer, the carrier supporting the catalytic metal (catalyst-supporting carrier) and the electrolyte may be mixed. The support for supporting the catalytic metal may be, for example, a carbon material such as carbon that is generally available commercially. The gas diffusion layer may be a conductive member having air holes. Examples of the conductive member include porous carbon materials such as carbon cloth and carbon paper, and porous metal members such as metal mesh and foamed metal. A cell of the fuel cell may include a separator. The separators collect the electric current generated by power generation and function as partition walls. In a fuel cell, the separators are usually arranged on both sides of the power generation section in the stacking direction so that the power generation section is sandwiched between a pair of separators. One of the pair of separators is an anode separator and the other is a cathode separator. The anode separator may have grooves that serve as hydrogen gas flow paths on the surface facing the power generation section. The cathode separator may have grooves that serve as reaction air channels on the surface facing the power generation section. The separator may have holes forming manifolds such as supply holes and discharge holes for circulating a fluid in the stacking direction of the cells. The separator may be made of, for example, dense carbon obtained by compressing carbon to make it gas impermeable, or a press-molded metal (for example, iron, titanium, stainless steel, etc.). The cell may include an insulating resin frame disposed on the outer side (periphery) of the membrane electrode assembly in the planar direction between the anode separator and the cathode separator. The resin frame is molded into a plate-like and frame-like shape using a thermoplastic resin, and seals the gap between the anode separator and the cathode separator while holding the membrane electrode assembly in its central region. For the resin frame, for example, a resin such as PE, PP, PET, or PEN can be used. The resin frame may be a three-layer sheet composed of three layers with an adhesive layer disposed on the surface layer.

[0020] The fuel cell system may include a control device. The control device may control the reaction air system, the hydrogen system, the cooling air system, etc., and may control the entire fuel cell system. The control device physically has, for example, a processing device such as a CPU (central processing unit), a ROM (read-only memory) that stores control programs and control data processed by the CPU, a storage device such as a RAM (random access memory) that is mainly used as various working areas for control processing, and an input / output interface, and may be an ECU (electronic control unit), etc.

[0021] The reaction air system supplies reaction air to the fuel cell as an oxidant gas and adjusts the flow rate of the reaction air. The reaction air system may include a reaction air pipe and the like. The hydrogen system supplies hydrogen as a fuel gas to the fuel cell and adjusts the flow rate of the hydrogen, and may include a hydrogen tank, a hydrogen inlet valve, an injector, a gas-liquid separator, a hydrogen purge valve, an ejector for hydrogen circulation, a hydrogen pump for hydrogen circulation, and hydrogen piping. The cooling air system supplies cooling air as a cooling gas to the fuel cell, and adjusts the flow rate of the cooling air.

[0022] The reaction air system has an inlet-side sealing valve at the inlet of the reaction air of the fuel cell, and an outlet-side sealing valve at the outlet of the reaction air of the fuel cell. In the present disclosure, the fuel cell has an independent flow path structure for the reaction air and the cooling air, and valves (an inlet side sealing valve and an outlet side sealing valve) are installed at the inlet and outlet of the reaction air of the fuel cell in the reaction air system, making it possible to seal the cathode of the fuel cell with a smaller volume than when the fuel cell has a flow path structure in which the reaction air and the cooling air are common.

[0023] The reaction air system may have a reaction air blowing means, the cooling air system may have a cooling air blowing means, and the hydrogen exhaust flow path of the hydrogen system may merge with the cooling air exhaust flow path of the cooling air system. The hydrogen exhaust flow path of the hydrogen system may further have a junction part that can merge with the reaction air exhaust flow path of the reaction air system. By having independent blowing means for the reaction air system and the cooling air system, and by having the hydrogen exhaust flow path merge with the cooling air exhaust flow path, when the system is shut down, the fuel cell system can stop the reaction air blowing means and drive the cooling air blowing means, thereby diluting the exhausted hydrogen with cooling air and discharging it outside the fuel cell system. The reaction air blowing means and the cooling air blowing means may be an air compressor, an air pump, an air blower, an air fan, or the like, respectively. The reaction air system may have a reaction air intake port for taking in reaction air from outside the fuel cell system, and the reaction air intake port may be provided with a pressure loss body such as an air filter. The cooling air system may have a cooling air intake port through which cooling air is taken in from outside the fuel cell system, and the cooling air intake port may be provided with a pressure loss body such as an air filter.

[0024] When the fuel cell system is shut down, it continues to supply hydrogen and cooling air to the fuel cell, but stops the supply of reaction air to the fuel cell, closes the reaction air inlet sealing valve and the reaction air outlet sealing valve to seal the cathode of the fuel cell, and then stops the supply of hydrogen to the fuel cell while continuing to supply cooling air to the fuel cell intermittently or continuously. "After that" may be after a predetermined time has elapsed, or may be after the voltage of the fuel cell has dropped below a predetermined voltage. The fuel cell system may also isolate the cathode and anode of the fuel cell from the outside of the fuel cell system when the system is shut down.

[0025] Deterioration of the fuel cell can be prevented by shutting down the fuel cell system using the shutdown sequence below. (1) Stop sequence 1 If necessary, perform scavenging and draining of the fuel cell, turn off the air blower, and close the inlet and outlet sealing valves of the reaction air system to seal the reaction air system. (2) Stop sequence 2 Then, the hydrogen system is purged and drained. The hydrogen purge valve may be opened and closed. At this time, the cooling fan may be turned on intermittently or continuously to dilute and exhaust the hydrogen. After the fuel cell voltage drops to a predetermined value, the hydrogen purge valve and hydrogen inlet valve are closed to seal off the hydrogen system. If the hydrogen purge valve is shut off, the hydrogen inlet valve may be closed after the cooling fan is shut off. Since closing the hydrogen purge valve stops the flow of hydrogen and there is no need to dilute the hydrogen, the cooling fan may be shut off before, after, or at the same time as closing the hydrogen inlet valve. When the fuel cell is finished generating electricity, the cathode is sealed first, then the hydrogen system is purged by opening and closing the hydrogen purge valve, and the hydrogen system is then sealed. This allows the fuel cell to be sealed in a hydrogen-rich state, and prevents deterioration due to abnormal potential of the fuel cell while it is stopped. If the anode is sealed before the cathode is sealed, oxygen will continue to flow into the cathode, which may cause a hydrogen shortage within the fuel cell and result in an abnormal potential state. In order to seal the cathode in a small volume, the reaction air and the cooling air are provided with independent flow passage structures. Since it is necessary to dilute and exhaust the purged hydrogen after sealing the cathode, a blowing means may be provided for each of the reaction air system and the cooling air system. When the oxygen concentration decreases after the cathode is sealed, and the voltage of the fuel cell drops, an amount of hydrogen equivalent to or greater than the amount of residual oxygen is secured, and the supply of hydrogen can be stopped. If there is a large amount of liquid water in the fuel cell at the end of power generation and flooding is occurring, the flow rate of the air blower and hydrogen pump may be increased to perform scavenging and drainage treatment of the fuel cell before sealing the reaction air system.

[0026] The fuel cell system may include an electrical system. The electrical system may have a diode on the power line to the fuel cell, and may further have a relay for the fuel cell. By having a diode, it is possible to prevent the occurrence of reverse current from the power line to the fuel cell. A power consumption absorbing means such as a secondary cell (battery) or a capacitor is connected to the power line. In the fuel cell system, the fuel cell may be connected to the power line of the electrical system when the system is stopped. This makes it possible to prevent the fuel cell from reaching a high potential during scavenging, and to reduce the voltage of the fuel cell in a short period of time. By performing the shutdown process while the fuel cell is connected to the power line via a diode, the potential of the fuel cell can be constantly maintained at or below V2. If the above process is performed in an open circuit state with the relay turned off, the fuel cell voltage will reach a high potential (over 0.9 V) of the open circuit voltage (OCV), and the fuel cell will deteriorate. V2 may be set by a power consumption absorption means such as a connected battery or capacitor so that the fuel cell voltage is within an operating range of less than 0.85 V. Furthermore, by absorbing power using the power consumption absorption means after sealing the cathode, oxygen is quickly consumed by power generation, and the shutdown process can be completed in a short time.

[0027] The hydrogen system may have a hydrogen pump for circulation. By providing a hydrogen pump, scavenging and drainage can be performed efficiently with a small amount of hydrogen. In addition, the hydrogen concentration in the fuel cell can be quickly equalized, preventing deterioration of the fuel cell due to localized hydrogen deficiency. During shutdown sequence 2, the hydrogen system is circulated using a hydrogen pump, allowing for drainage and scavenging while suppressing hydrogen emissions. Also, during shutdown sequences 1 and 2, localized hydrogen shortages (=abnormal potential) can be prevented.

[0028] FIG. 1 is an exploded perspective view showing an example of a single cell of a fuel cell provided in a fuel cell system of the present disclosure. 1 includes cooling fins (cooling air flow paths) 2 that serve as flow paths for cooling air (cooling gas) 7, a reaction air inlet 3, a reaction air outlet 4, a hydrogen gas inlet 5, a hydrogen gas outlet 6, two separators 11, and an MEA and a resin frame 12 sandwiched between the two separators 11. As shown in FIG. 1, the fuel cell 1 has a flow path structure in which the reaction air 9 and the cooling air 7 are independent of each other.

[0029] FIG. 2 is a schematic perspective view showing an example of a fuel cell stack included in the fuel cell system of the present disclosure. The fuel cell stack shown in FIG. 2 is a laminate in which a plurality of cells 1 are stacked, and includes a current collector plate 13 and a pressure plate 14 on both ends in the stacking direction.

[0030] FIG. 3 is a system configuration diagram showing an example of a fuel cell system according to the present disclosure. The fuel cell system shown in Fig. 3 includes a fuel cell stack 10, a reaction air system 20, a cooling air system 30, and a hydrogen system 40. The reaction air system 20 includes a reaction air intake port 21, an air blower 22, an inlet side sealing valve 23, and an outlet side sealing valve 24. The cooling air system 30 includes a cooling fan 31. The hydrogen system 40 includes a hydrogen tank 41, a hydrogen inlet valve 42, a gas-liquid separator 43, a hydrogen purge valve 44, and a hydrogen pump 45. The fuel cell system shown in Fig. 3 includes sealing valves 23, 24 at the inlet and outlet of the reaction air system 20, and includes independent blowing means 22, 31 for the reaction air system 20 and the cooling air system 30.

[0031] FIG. 4 is a circuit diagram showing an example of an electrical system included in the fuel cell system of the present disclosure. The electrical system 50 shown in FIG. 4 includes a power line 51, a diode 52, a relay 53, a power consumption absorbing means 54 such as a battery / capacitor, auxiliary equipment 55, and a power consumption device 56. By installing a diode 52 on the power line 51 and connecting the fuel cell stack 10 to the power line 51 during recovery control, it is possible to shorten the recovery control time while avoiding the occurrence of reverse current from the power line 51 to the fuel cell stack 10.

[0032] FIG. 5 is a flowchart showing an example of control of the fuel cell system of the present disclosure. FIG. 5(1) shows the shutdown sequence of a fuel cell system. At the start of the shutdown sequence, the hydrogen inlet valve is open, the cooling fan is on, the reaction air sealing valve (the inlet side sealing valve and the outlet side sealing valve) is open, and the reaction air blower is on. The reaction air seal valve is closed to seal the reaction air system. The hydrogen purge valve is opened intermittently to begin scavenging the hydrogen system. When the voltage of the fuel cell drops to a predetermined value, the hydrogen inlet valve and hydrogen purge valve are closed, the cooling fan is stopped, and the control ends.

[0033] FIG. 5(2) shows the shutdown sequence for a fuel cell system configuration including a hydrogen pump, relay, and diode. When the shutdown sequence begins, the hydrogen inlet valve is open, the hydrogen pump is on, the cooling fan is on, the reaction air sealing valve (the inlet side sealing valve and the outlet side sealing valve) is open, the reaction air blower is on, and the relay is on. The fuel cell is scavenged. The scavenging process may be performed for 5 seconds at a high flow rate of reaction air (a stoichiometric ratio of 3 or more when power is being generated, or a flow rate that can move droplets in the flow path when power is not being generated). Thereafter, the reaction air sealing valve is closed to seal the reaction air system. Thereafter, the scavenging process of the hydrogen system is started. The scavenging process of the hydrogen system may be carried out by circulating the hydrogen pump at a high flow rate for a certain period of time while intermittently opening the hydrogen purge valve. A group of data showing the pressure fluctuation when the hydrogen purge valve is opened or the relationship between the cell temperature and the required scavenging time may be prepared in advance, and scavenging may be determined to be complete when the required scavenging time has elapsed. After scavenging is determined to be complete, the hydrogen pump is turned off. After turning off the hydrogen pump, a final purge of the hydrogen system is performed to drain liquid water and other substances that have accumulated in the gas-liquid separator. The final purge of the hydrogen system may be performed by intermittently opening the hydrogen purge valve with the hydrogen pump turned off. After the final purge of the hydrogen system is completed, the exhaust hydrogen is diluted with cooling air and exhausted to the outside of the fuel cell system, after which the hydrogen purge valve is closed and the cooling fan is turned off. The fuel cell voltage may be monitored, and the relay may be turned off after the average cell voltage falls below 0.4 V. After the relay is turned off, the hydrogen inlet valve is closed to seal off the hydrogen system, and control is terminated.

[0034] FIG. 6 is a flowchart showing another example of the control of the fuel cell system of the present disclosure. As shown in FIG. 6, from the viewpoint of shortening the time required for the shutdown process, the scavenging process for the hydrogen system may be performed in parallel with the scavenging process for the fuel cell and the shutdown process for the electrical system. After sealing the reaction air system, the occurrence of abnormal electrical potential in the fuel cell can be prevented by shutting down the electrical system, performing a final purge of the hydrogen system (diluting and evacuating using cooling air), and then sealing the hydrogen system. [Explanation of symbols]

[0035] 1. Cell 2. Cooling fins (cooling air flow path) 3.Reaction air inlet 4.Reaction air outlet 5. Hydrogen gas inlet 6. Hydrogen gas outlet 7. Cooling air (cooling gas) 8. Hydrogen gas 9.Reaction air 10. Fuel Cell Stack 11. Separator 12.MEA, resin frame 13. Current collector plate 14. Pressure plate 20.Reaction air system 21.Reaction air intake 22. Air Blower 23. Inlet side sealing valve 24.Outlet side sealing valve 30. Cooling air system 31. Cooling fan 40. Hydrogen 41. Hydrogen tank 42. Hydrogen inlet valve 43. Gas-liquid separator 44. Hydrogen purge valve 45. Hydrogen pump 50. Electrical system 51. Power Lines 52. Diode 53. Relay 54. Means of absorbing power consumption 55. Auxiliary equipment 56.Power consumption equipment

Claims

1. An air-cooled fuel cell system, the fuel cell system includes a fuel cell, a hydrogen system that supplies hydrogen to the fuel cell, a reaction air system that supplies reaction air to the fuel cell, and a cooling air system that supplies cooling air to the fuel cell; the fuel cell has a reaction air flow path and a cooling air flow path having an independent flow path structure for the reaction air and the cooling air, the reaction air system has an inlet-side sealing valve at an inlet of the reaction air of the fuel cell, and an outlet-side sealing valve at an outlet of the reaction air of the fuel cell, The fuel cell system is characterized in that, when the system is shut down, the supply of reaction air to the fuel cell is stopped while continuing the supply of hydrogen to the fuel cell and the supply of cooling air to the fuel cell, and the inlet side sealing valve and the outlet side sealing valve are closed to seal the cathode of the fuel cell, and then the supply of hydrogen to the fuel cell is stopped while continuing the supply of cooling air to the fuel cell intermittently or continuously.

2. The reaction air system has a reaction air blowing means, The cooling air system includes a cooling air blowing means, 2. The fuel cell system according to claim 1, wherein the hydrogen discharge flow passage of the hydrogen system merges with a cooling air discharge flow passage of the cooling air system.

3. The fuel cell system includes an electrical system; 2. The fuel cell system according to claim 1, wherein the fuel cell system connects the fuel cell to a power line of the electrical system when the system is stopped.

4. 2. The fuel cell system according to claim 1, wherein the hydrogen system comprises a hydrogen pump.

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